Disorders involving deficient impulse-control-including child conduct disorder and attention- deficit/hyperactivity disorder, adult antisocial personality disorder, and alcohol/drug dependence (collectively known as externalizing disorders)-are debilitating for afflicted individuals and costly to society, and research is needed to clarify the biological basis of disorders of this kind. Because of its unique advantages as a measurement tool (e.g., high time-resolution;mapping of signal frequencies;cost-effectiveness), electrocortical (EEG/ERP) recording is a crucial tool in efforts to conceptualize and index externalizing-proneness neurobiologically. The proposed research will advance knowledge about the neurophysiological substrates of externalizing disorders by applying new approaches for analyzing electrocortical (EEG/ERP) data to an investigation of neural processing deficits underlying proneness to externalizing problems. Two innovative analytic approaches will be utilized: (1) psychometric modeling methods, which have been valuable for isolating variance in ERP measures most indicative of externalizing-related processing deviations (Nelson, Patrick, &Bernat, in press), and (2) EEG time-frequency (TF) analysis, an effective tool for partitioning overlapping components of the ERP signal that show differential relations with externalizing. Primary ERP measures of interest include: (1) variants of the P300, an index of cognitive processing known to function as an endophenotype of externalizing proneness, and (2) the error-related negativity (ERN), a measure of on-line performance monitoring. As a follow-up to Nelson et al. (in press), this proposed work aims: (1) to determine whether previously-documented relationships between ERN amplitude reduction and externalizing proneness generalize to ERN measures captured from differing task conditions, (2) to examine, using TF signal analysis and psychometric analytic methods, the degree to which ERN and P300 amplitude reductions reflect unique or interrelated neural deficits associated with externalizing, and (3) to determine whether multivariate psychophysiological composite variables reliably outperform individual ERP variables in predicting externalizing proneness. By refining measurement of neurophysiological indicators of disinhibition, this research promises to yield improved methods for identifying individuals at biological risk for the development of disinhibitory psychopathology, and for defining subgroups in neuroimaging, neurochemical, and genetic studies of mechanisms underlying disorders of impulse control. Further, the findings will yield neurophysiological target variables suitable for use in diagnostic and treatment-response studies. PUBLIC HEALTH RELEVANCE: Impulse control disorders, including antisociality and addictions, are serious public health problems. This research will utilize innovative new EEG/ERP methods to advance understanding of neuro-cognitive deficits underlying proneness to disorders of this kind. Findings will yield improved brain indicators of underlying risk that can serve as targets for diagnosis and treatment monitoring.